Caption: Sand food plants (Pholisma sonorae). These mushroom-shaped parasitic plants are native to the deserts of south-western USA and Mexico. They are found growing on shifting sand dunes. Their scaly stems were eaten raw or cooked by Native Americans. They contain no chlorophyll and therefore cannot produce their own food. Instead, their stems, which extend 1-2 metres below the ground, are attached to the roots of nearby host plants. This unusual plant has become endangered. It is threatened by off-road vehicles and the development of the desert. Photographed in the Algodones wilderness, California, USA.